PSA spikes are poor predictors of prostate cancer

CHICAGO (Reuters) - A sudden spike in blood levels of prostate specific antigen, or PSA, is not an accurate way to predict prostate cancer, and testing for such changes can lead to overtreatment, U.S. researchers said on Thursday.

Several groups including the National Cancer Center Network and the American Urological Association recommend that men with a spike in PSA -- known as high PSA velocity -- get a biopsy for prostate cancer, even if there are no other indicators that cancer may exist.

"We have found no evidence to support the recommendation that men with a high PSA velocity should be biopsied in the absence of other indications," said Andrew Vickers of Memorial Sloan-Kettering Cancer Center in New York, whose study appears in the Journal of the National Cancer Institute.

Those other indications could be an elevated total PSA level or a positive digital rectal exam, he said.

"In other words, if a man's PSA has risen rapidly in recent years, there is no cause for concern if his total PSA level is still low and his clinical exam is normal," Vickers said in a statement.

Prostate cancer kills about 250,000 men a year globally and is the second most common cause of cancer death in men in the United States, after lung cancer.

Blood tests that measure overall levels of PSA have reduced prostate cancer-related deaths, but PSA testing identifies many slow-growing cancers that may never need treatment.

Vickers' team looked to see how effective PSA velocity is a tool for predicting prostate cancer.

The team studied more than 5,000 men over 55 who were participating in a study of Merck & Co Inc's finasteride -- sold as Proscar and Propecia -- a drug commonly used to treat enlargement of the prostate gland.

The team focused on men in the placebo group who were followed with yearly PSA tests. After seven years, all men in the study underwent a biopsy.

Based on these tests, the team found no important link between a sudden rise in PSA levels and prostate cancer, noting that an elevated PSA level was a much better way to predict prostate cancer.

"This study should change practice," Dr. Peter Scardino, chair of surgery at Memorial Sloan-Kettering, said in a statement.

He said the large study adds to others showing that changes in PSA should not be used alone as a basis for getting a biopsy. Besides cancer, other conditions, including an enlarged prostate and infections, can cause PSA levels to rise.

Once diagnosed, more than 90 percent of men with low-grade prostate cancer get treated, most often with surgery or radiation. Both can cause lasting side effects including impotence or incontinence.